Ultrahigh-strength prestressed concrete pipe pile and preparation method thereof

Abstract

The invention discloses an ultrahigh-strength prestressed concrete pipe pile and a preparation method, and relates to the technical field of building materials. The ultrahigh-strength prestressed concrete pipe pile comprises a core layer which is composed of 1.0%-2.0% by volume of chopped basalt fiber reinforced concrete, the fiber length is 8-12 mm, the diameter is 15-20 microns, and the compressive strength is larger than or equal to 130 MPa; the transition layer is composed of hybrid fiber reinforced concrete with the volume fraction of 3.0%-4.0%, steel fibers account for 60%-75%, polyethylene fibers account for 25%-40%, the length-diameter ratio of the steel fibers is 50-80, and the tensile strength is larger than or equal to 1200 MPa. Through gradient fiber reinforced structure design and preparation process innovation, the mechanical property, the production efficiency and the environmental friendliness of the prestressed concrete pipe pile are synergistically improved. Firstly, in the aspect of mechanical properties, the compressive strength is made to break through 130 MPa through the synergistic effect of the core layer basalt fiber and the high-activity superfine slag powder and is improved by 30% or above compared with a traditional C100 pipe pile, and meanwhile the shear strength is improved to 18 MPa or above through a transition layer steel-polyethylene hybrid fiber system.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and specifically relates to an ultra-high-strength prestressed concrete pipe pile with a gradient reinforcement structure and a preparation method thereof. The ultra-high-strength prestressed concrete pipe pile is particularly suitable for deep foundation projects under complex geological conditions, and can significantly improve the compressive strength, impact resistance and durability of the pipe pile. Background Art

[0002] Prestressed concrete pipe piles are widely used as foundation components in civil engineering, and their performance optimization has always been a focus of technological innovation in the industry. Traditional pipe piles generally use concrete formulas with strength grades of C80-C100, and achieve mechanical performance requirements through high cement dosage (usually accounting for more than 70% of the total cementitious material) (such as patent CN101235638A), but this leads to a significant increase in concrete brittleness. Actual engineering cases have shown that when such pipe piles are constructed under complex geological conditions, longitudinal cracks caused by insufficient impact resistance are a prominent problem. For example, the pile foundation damage rate of a high-speed rail project is as high as 3.2%, which seriously threatens the safety of the structure. Although some technologies have attempted to alleviate local stress concentration by adding metal sleeves at the ends (such as patent CN222375377U), they have failed to systematically improve the overall crack resistance and toughness of the pipe piles, and the increased deadweight of the components has restricted their application in deep foundation engineering.

[0003] The energy consumption and environmental protection issues of the existing production process also need to be overcome. The current mainstream technology relies on the autoclave curing process (steam temperature ≥ 180°C, pressure 1.0MPa) to achieve concrete strength development (such as patent CN110792079A). The energy consumption of a single pipe pile production exceeds 120kWh, and the carbon emission intensity reaches 280kg CO2 / m 3 , which is significantly different from the “dual carbon” target requirements; in addition, the traditional centrifugal forming process has insufficient control over the distribution of fiber-reinforced materials, and the fibers are prone to agglomeration or sedimentation in concrete (reference patent CN118322335B equipment patent), resulting in limited improvement in mechanical properties; some improved technologies attempt to introduce low-temperature curing processes (such as patent CN119041415A), but their strength only reaches the C100 level, and the problem of fiber orientation control has not been solved, making it difficult to meet the industrial production needs of ultra-high-strength pipe piles.

[0004] In terms of connection reliability and environmental adaptability, traditional pipe piles mostly use on-site welded joints, which are prone to electrochemical corrosion when exposed to corrosive environments for a long time, resulting in a reduction in bearing capacity. Marine engineering monitoring data shows that the corrosion rate of welded joints in salt spray environments exceeds 15% over 5 years, posing the risk of leakage and structural failure (such as patent CN117702731A). At the same time, existing formulas do not make sufficient resource utilization of industrial solid waste. The content of alternative materials such as slag powder and residual slurry is generally less than 15% (patent CN101235638A), which not only increases production costs but also causes large amounts of solid waste to be stored. There is a significant gap between this and the requirement of a solid waste utilization rate of ≥30% in the "Green Building Evaluation Standard" (GB / T 50378). These technical bottlenecks have seriously restricted the promotion and application of prestressed concrete pipe piles in high-bearing-capacity, harsh environments and green construction scenarios. Summary of the Invention

[0005] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide an ultra-high strength prestressed concrete pipe pile and a preparation method thereof, which can solve the problems raised by the above-mentioned background technology.

[0006] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:.

[0007] Synergistic mechanism of gradient fiber reinforcement system

[0008] (1) Critical length design of core layer basalt fiber:

[0009] According to the Kelly-Tyson theory, the critical fiber length lc = σfd2τlc = 2τσfd (σfσf is the fiber strength, dd is the diameter, and ττ is the interface shear strength);

[0010] When the basalt fiber length is 8-12 mm (measured τ = 3.2 MPaτ = 3.2 MPa), the calculated lc = 7.5 11.3 mm lc = 7.5 11.3 mm matches the actual length and ensures effective fiber load-bearing (experimental data see Table 1).

[0011] (2) Toughening mechanism of hybrid fibers in transition layer:

[0012] Steel fibers inhibit crack propagation through bridging action, while polyethylene fibers absorb impact energy through high ductility;

[0013] When the proportion of steel fiber is greater than 60%, the shear strength is significantly improved, but excessive steel fiber (greater than 75%) will lead to a decrease in the workability of concrete (slump less than 120 mm).

[0014] (3) Orientation control technology of surface nanocarbon fibers:

[0015] High-frequency vibration (50 Hz) enables the nanofibers to overcome the van der Waals force in the centrifugal field and align radially;

[0016] Through SEM observation, when the fiber angle deviation is ≤10°, the impact toughness is increased by 2.3 times compared with random distribution.

[0017] Corrugated steel cylinder interface optimization and vent hole function verification

[0018] (1) Chemical anchor parameter optimization experiment:

[0019]

[0020] (2) Influence of vents on interface performance:

[0021] When the pore diameter is 1.0-2.0mm, the moisture content at the interface between the steel cylinder and concrete decreases by 40% during the curing period;

[0022] Finite element simulation shows that when the hole spacing is 1 / 2 of the peak spacing, the axial stiffness of the pile is only reduced by 4.7% (the control group with no hole structure reduced by 12.3%).

[0023] 2.4 Temperature control logic and strength development model of autoclave-free curing system

[0024] (1) Hydration kinetics of slag powder in the pre-curing stage:

[0025] After curing at 40℃ for 12 hours, the hydration degree of slag powder reaches 35%-40%, and the amount of CSH gel generated is 50% higher than that of curing at room temperature;

[0026] When the humidity is ≥95%, the capillary porosity of the core layer concrete is ≤8% (mercury intrusion method test).

[0027] (2) Strength prediction model for low-temperature steam curing:

[0028] Based on the Arrhenius equation, the equivalent age of 60℃ curing is te=t·eEaR(1293-1T)te=t·eREa(2931-T1)(Ea=40kJ / molEa=40kJ / mol);

[0029] It is calculated that 8 hours of curing is equivalent to 82% of the strength development of 7 days at 20°C, which deviates from the measured value by less than 5%.

[0030] The preparation process of carbon fiber reinforced nylon ring includes:

[0031] Material ratio: nylon 66 matrix 50%-60%, carbon fiber (length 3-6mm) 40%-50%, coupling agent (silane KH-560) 0.5%-1.0%;

[0032] Molding process: Injection molding at 280-300℃, holding pressure 80-100MPa, cooling rate 10-15℃ / min;

[0033] Performance indicators: Ring tensile strength ≥800MPa, interface bonding strength with concrete ≥4.0MPa (refer to GB / T50152).

[0034] Supporting experimental data:

[0035] Table 1 Effect of core layer basalt fiber length on compressive properties:

[0036] Fiber length (mm) Compressive strength (MPa) <![CDATA[Fracture propagation energy (J / m 2 )]]> 6 118.4 48.3 8 125.7 62.1 12 132.6 75.8 15 130.2 69.5 (fiber agglomeration)

[0037] Table 2 Effect of steel fiber ratio in transition layer on shear strength:

[0038] Steel fiber proportion (%) Shear strength (MPa) Slump (mm) 50 16.3 135 60 18.7 125 70 19.5 110 80 18.9 95(Segregation Risk)

[0039] A method for preparing ultra-high strength prestressed concrete pipe piles comprises the following steps:

[0040] (1) Step-by-step centrifugal molding:

[0041] Step 1: Fix the corrugated steel cylinder in the center of the mold, inject the core layer concrete, and centrifuge at 800-1000 rpm for 5 minutes with a centrifugal acceleration of 0.5-0.8g;

[0042] Step 2: Inject the transition layer concrete, and reduce the centrifugal speed linearly from 1200 rpm to 800 rpm for 3 minutes, while applying 30-50 Hz axial vibration simultaneously;

[0043] Step 3: Pour into the surface concrete, centrifuge at 1500-1800 rpm for 3 minutes, and simultaneously apply 50-60 Hz high-frequency vibration;

[0044] (2) Autoclave-free curing:

[0045] Pre-curing stage: Place in a curing box at a temperature of 40±2℃ and relative humidity ≥95% for 12 hours;

[0046] Low temperature steam curing: heat up to 60℃ at 3-5℃ / h, maintain constant temperature for 8 hours, steam pressure ≤0.1MPa;

[0047] Natural curing stage: After demoulding, cure in an environment of 20-25℃ and humidity ≥80% for 7 days.

[0048] The axial vibration of the transition layer during centrifugation is applied in the following manner:

[0049] The angle between the vibration direction and the pile axis is 15-30°, and the vibration energy density is 0.5-1.0 J / cm 3;

[0050] Vibration timing control: delay vibration for 10-20 seconds after starting centrifugation to avoid disturbance before initial setting of concrete.

[0051] The pre-setting process of the self-healing microcapsules includes:

[0052] Spraying equipment: using dual-fluid nozzle, atomization pressure 0.2-0.4MPa, spray distance 100-150mm;

[0053] Microcapsule layer thickness: 0.5-1.0mm, coverage ≥90%, drying temperature 40-50℃, drying time 2-3 hours.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] This invention achieves a synergistic improvement in the mechanical properties, production efficiency, and environmental friendliness of prestressed concrete pipe piles through innovative gradient fiber-reinforced structural design and preparation processes. First, in terms of mechanical properties, the synergistic effect of the core layer basalt fiber and highly active slag powder enables the compressive strength to exceed 130MPa, which is more than 30% higher than that of traditional C100 pipe piles. At the same time, the transition layer steel-polyethylene hybrid fiber system increases the shear strength to more than 18MPa, and the directional arrangement of the surface nano-carbon fibers enables the impact toughness to reach 15kJ / m 2 The piles exhibit excellent resistance to chloride ion penetration (electric flux ≤ 800°C) and crack self-repair capabilities (28-day repair rate ≥ 80%), extending their estimated service life to 50 years in marine corrosive environments, nearly double that of traditional piles.

[0056] In terms of production process optimization, the combination of step-by-step centrifugal forming and autoclave-free curing technology significantly reduces energy consumption and costs. The gradient centrifugation process (core layer 800-1000rpm, transition layer 1200→800rpm, surface layer 1500rpm) improves the fiber distribution uniformity to more than 85% through the synergistic effect of vibration-centrifugation, avoiding the fiber sedimentation problem of traditional processes. Low-temperature steam curing (60°C constant temperature for 8 hours) replaces the traditional 180°C autoclave curing. The energy consumption of single pipe pile production is reduced from 120kWh to 82kWh, a decrease of 40%. At the same time, the demoulding strength still reaches more than 70% of the design strength. The embedded carbon fiber connecting ring structure simplifies the on-site construction process, increases the installation efficiency by 50%, and the joint sealing (no leakage at 1.2MPa water pressure) is better than the traditional welding process.

[0057] In terms of resource recycling and low-carbon environmental protection, this invention achieves efficient utilization of industrial solid waste and a significant reduction in carbon emissions. The solid waste replacement rate of slag powder, iron tailings powder and residual slurry in the core layer formula exceeds 50%, and the cement consumption of a single pipe pile is reduced by 30%, and the carbon emission intensity is reduced to 180kg CO2 / m 3 , a 35% reduction compared to traditional processes. Self-healing microcapsule technology reduces material waste associated with pipe pile maintenance. Its microbial remediation agent carrier, modified with discarded shell powder, further expands solid waste utilization. Calculations show that, in large-scale production, every 10,000 meters of pipe pile can dispose of 12,000 tons of steelmaking waste slag and 6,000 tons of residual slurry, reducing CO2 emissions by 15,000 tons, fully meeting the three-star evaluation criteria of the "Technical Requirements for Green Building Materials Product Certification." BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0059] Figure 1 It is a structural schematic diagram of the pipe pile of the present invention;

[0060] Figure 2 It is a cross-sectional view of the pipe pile of the present invention. DETAILED DESCRIPTION

[0061] Example 1: Preparation of standard ultra-high-strength prestressed concrete pipe piles

[0062] 1. Raw materials and formula

[0063] (1) Core layer concrete (mass percentage):

[0064] P·II 52.5 cement: 12%

[0065] S95 grade slag powder: 18%

[0066] 450 mesh iron tailings powder: 10%

[0067] Basalt coarse aggregate (5-20mm continuous grading): 50%

[0068] Machine-made sand (fineness modulus 3.0): 25%

[0069] Polycarboxylate water reducer: 0.5%

[0070] Self-healing additive (Bacillus + nano calcium carbonate): 2%

[0071] (2) Transition layer mixed fibers:

[0072] Steel fiber (aspect ratio 60, tensile strength 1250 MPa): 3.0 vol%

[0073] Polyethylene fiber (length 18 mm, KH-550 modified): 1.0 vol%

[0074] (3) Surface nanocarbon fibers:

[0075] Nanocarbon fibers (diameter 80 nm, length 1.0 mm): 5.5 vol%

[0076] Sodium polyacrylate dispersant: 0.2% (based on cement mass)

[0077] 2. Preparation process

[0078] (1) Step-by-step centrifugal molding:

[0079] Core layer: Preheat the mold with pre-fixed corrugated steel cylinder (peak spacing 22mm) to 30℃, inject the core layer concrete, and centrifuge at 900 rpm for 5 minutes (acceleration 0.6g);

[0080] Transition layer: After the transition layer concrete was injected, the centrifugal speed was linearly reduced from 1200 rpm to 800 rpm (taking 3 minutes), and 40 Hz axial vibration (amplitude 0.2 mm) was applied simultaneously;

[0081] Surface layer: After injecting the surface concrete, centrifuge at 1600 rpm for 3 minutes and simultaneously apply 55 Hz high-frequency vibration.

[0082] (2) Maintenance system:

[0083] Pre-curing: curing at 40℃ and 95% humidity for 12 hours;

[0084] Low temperature steam curing: heat up to 60°C at 4°C / h and maintain constant temperature for 8 hours;

[0085] Natural curing: Curing at room temperature for 7 days after demoulding.

[0086] 3. Performance Testing and Results

[0087]

[0088] Example 2: Preparation of highly corrosion-resistant pipe piles for marine engineering

[0089] 1. Improvements

[0090] (1) Surface modification: Add 0.5% graphene modifier (specific surface area 300m 2 / g), improving the resistance to chloride ion corrosion;

[0091] (2) Optimization of the connecting ring: a carbon fiber nylon ring (fiber content 45 wt%) with a 316L stainless steel insert is used, and a titanium alloy anti-corrosion layer is added to the sealing groove;

[0092] (3) Microcapsule formulation: 0.1% corrosion inhibitor (benzotriazole) was additionally added to the self-healing microcapsules.

[0093] 2. Key process parameters

[0094] Surface centrifugal speed: 1700rpm, vibration frequency 60Hz;

[0095] Steam curing stage: constant temperature 60°C, relative humidity 85% (simulating high humidity environment of the ocean).

[0096] 3. Corrosion resistance test

[0097]

[0098] Example 3: Low-cost and environmentally friendly pipe pile preparation

[0099] 1. Raw material substitution

[0100] (1) Core layer cement replacement:

[0101] Slag powder: 25% (replaces part of cement)

[0102] Fly ash (grade II): 15%

[0103] (2) Aggregate replacement: 100% recycled concrete aggregate (particle size 5-20 mm, crushing value ≤ 12%);

[0104] (3) Water reducer optimization: Use lignin sulfonate composite water reducer (cost reduction of 40%).

[0105] 2. Process adjustment

[0106] The centrifugal speed is reduced: core layer 800rpm, transition layer 1000→700rpm;

[0107] Curing temperature adjustment: pre-curing 35℃, low-temperature steam curing 55℃.

[0108] 3. Comparison of economic efficiency and environmental protection

[0109]

[0110] Experimental design

[0111] 1.Fiber distribution uniformity test

[0112] Methods: The cross section of the pile was cut and the fiber distribution in the transition layer was analyzed using Image-Pro Plus software. The fiber spacing coefficient of variation (CV) was considered acceptable when it was ≤15%.

[0113] Results: Example 1 CV = 12.3%, Example 2 CV = 10.8%.

[0114] 2. Self-healing performance verification

[0115] Steps: Prefabricate cracks with a width of 0.3 mm and soak them in simulated groundwater with a pH of 10.5 for 28 days;

[0116] Evaluation: Crack width repair rate = (initial width - residual width) / initial width × 100%;

[0117] Data: The repair rate of Example 1 is 82%, and the repair rate of Example 2 is 89% (synergistic effect of microcapsule corrosion inhibitor).

[0118] 3. Connection structure sealing test

[0119] Method: Apply 1.2MPa water pressure to the connection joint and maintain it for 30 minutes;

[0120] Qualified standard: leakage ≤ 0.1L / min:

[0121] Results: The leakage rate of Example 2 was 0.05 L / min, and that of the traditional welded joint was 0.38 L / min.

[0122] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the scope of the present invention.

Claims

1. An ultra-high strength prestressed concrete pipe pile, characterized in that: include: (a) Three-layer gradient fiber reinforced structure, from inside to outside: Core layer: composed of 1.0%-2.0% volume fraction of chopped basalt fiber reinforced concrete, fiber length 8-12mm, diameter 15-20μm, compressive strength ≥130MPa; Transition layer: composed of hybrid fiber reinforced concrete with a volume fraction of 3.0%-4.0%, of which steel fiber accounts for 60%-75%, polyethylene fiber accounts for 25%-40%, steel fiber aspect ratio is 50-80, and tensile strength is ≥1200MPa; Surface layer: composed of 5.0%-6.0% volume fraction of nano-carbon fiber reinforced concrete, with fiber diameter of 50-100nm and length of 0.5-1.2mm. The fiber is radially oriented by the synergistic effect of high-frequency vibration and centrifugation, and the angle deviation of the arrangement is ≤10°; (b) A built-in corrugated steel cylinder with a wall thickness of 2.0-3.0 mm, a peak height of 5-8 mm, a peak spacing of 20-25 mm, and air holes with a diameter of 1.0-2.0 mm uniformly arranged on the surface, with the hole spacing being 1 / 2-1 / 3 of the peak spacing; (c) Annular metal sleeves are provided at both ends of the pile. The sleeve is 3-5 mm thick and the inner wall is pre-coated with a self-healing microcapsule layer. The microcapsules have a particle size of 0.5-2.0 mm and contain Bacillus subtilis and calcium silicate repair agents. The microcapsule rupture threshold pressure is 0.5-1.0 MPa.

2. The ultra-high strength prestressed concrete pipe pile according to claim 1, characterized in that: The components of the core layer concrete include, by mass percentage: P·II 52.5 grade Portland cement 10%-12%, specific surface area ≥500m 2 / kg S95 grade slag powder 15%-18%, fineness 450-500 mesh iron tailings powder 8%-10%; 45%-50% of continuously graded basalt coarse aggregate with a particle size of 5-20mm, and 20%-25% of manufactured sand with a fineness modulus of 2.8-3.2; 0.3%-0.5% of polycarboxylic acid-based high-performance water reducer and 1%-2% of self-healing additive, wherein the self-healing additive comprises Bacillus spores (concentration ≥1×10 6 CFU / g) and nano calcium carbonate carrier.

3. The ultra-high strength prestressed concrete pipe pile according to claim 2, characterized in that: The mixing ratio of the steel fiber and the polyethylene fiber in the transition layer is 2:1-3:1 (mass ratio), wherein: The surface of the steel fiber is treated with zinc phosphate coating with a coating thickness of 2-5μm and an interface bonding strength with concrete of ≥1.8MPa; The polyethylene fiber is high-density polyethylene (HDPE), the surface of which is modified by a gamma-aminopropyltriethoxysilane (KH-550) coupling agent, and the coating amount of the modifier is 0.5%-1.0% of the fiber mass.

4. The ultra-high strength prestressed concrete pipe pile according to claim 3, characterized in that: The directional arrangement of the surface carbon nanofibers is achieved by the following process: Centrifugal stage: at a speed of 1500-1800 rpm, the centrifugal acceleration is 1.2-1.5g; Vibration stage: synchronously apply axial high-frequency vibration, vibration frequency 50-60Hz, amplitude 0.05-0.1mm; Fiber dispersant: Add 0.1%-0.3% of sodium polyacrylate dispersant to the cement mass to ensure that the fiber dispersion uniformity is ≥90%.

5. The ultra-high strength prestressed concrete pipe pile according to claim 4, characterized in that: The interface connection between the corrugated steel cylinder and the concrete is as follows: Chemical anchor bolts: diameter 6-8mm, spacing 50-80mm, implantation depth ≥20mm, anchor bolt material is 304 stainless steel; Anchoring agent: It is composed of epoxy resin matrix and 20%-30% nano-SiO2 filler. After curing, the shear strength is ≥5.0MPa; Function of air vents: water vapor diffusion rate during the curing stage ≥ 0.15g / (m 2 ·s) to avoid interface hollowing defects.

6. A method for preparing the ultra-high strength prestressed concrete pipe pile according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Step-by-step centrifugal molding: Step 1: Fix the corrugated steel cylinder in the center of the mold, inject the core layer concrete, and centrifuge at 800-1000 rpm for 5 minutes with a centrifugal acceleration of 0.5-0.8g; Step 2: Inject the transition layer concrete, and reduce the centrifugal speed linearly from 1200 rpm to 800 rpm for 3 minutes, while applying 30-50 Hz axial vibration simultaneously; Step 3: Pour into the surface concrete, centrifuge at 1500-1800 rpm for 3 minutes, and simultaneously apply 50-60 Hz high-frequency vibration; (2) Autoclave-free curing: Pre-curing stage: Place in a curing box at a temperature of 40±2℃ and relative humidity ≥95% for 12 hours; Low temperature steam curing: heat up to 60℃ at 3-5℃ / h, maintain constant temperature for 8 hours, steam pressure ≤0.1MPa; Natural curing stage: After demoulding, cure in an environment of 20-25℃ and humidity ≥80% for 7 days.

7. The method for preparing an ultra-high strength prestressed concrete pipe pile according to claim 6, characterized in that: The axial vibration of the transition layer during centrifugation is applied in the following manner: The angle between the vibration direction and the pile axis is 15-30°, and the vibration energy density is 0.5-1.0 J / cm 3 ; Vibration timing control: delay vibration for 10-20 seconds after starting centrifugation to avoid disturbance before initial setting of concrete.

8. The method for preparing an ultra-high strength prestressed concrete pipe pile according to claim 7, characterized in that: The pre-setting process of the self-healing microcapsules includes: Spraying equipment: using dual-fluid nozzle, atomization pressure 0.2-0.4MPa, spray distance 100-150mm; Microcapsule layer thickness: 0.5-1.0mm, coverage ≥90%, drying temperature 40-50℃, drying time 2-3 hours.

9. The ultra-high strength prestressed concrete pipe pile according to any one of claims 1 to 5, characterized in that: The end connection structure is: Pre-embedded carbon fiber reinforced nylon ring, the outer diameter of the ring and the inner diameter of the pile have a tolerance of H7 / g6; Sealing structure: Two sealing grooves with trapezoidal cross-sections are opened on the surface of the ring body, with a depth of 1.5-2.0mm. EPDM rubber rings (hardness 70±5 Shore A) and 316L stainless steel bushings (thickness 0.2-0.5mm) are embedded in the grooves in sequence.

10. The ultra-high strength prestressed concrete pipe pile according to claim 9, characterized in that: The preparation process of the carbon fiber reinforced nylon ring includes: Material ratio: nylon 66 matrix 50%-60%, carbon fiber (length 3-6mm) 40%-50%, coupling agent (silane KH-560) 0.5%-1.0%; Molding process: Injection molding at 280-300℃, holding pressure 80-100MPa, cooling rate 10-15℃ / min; Performance indicators: Ring tensile strength ≥800MPa, interface bonding strength with concrete ≥4.0MPa (refer to GB / T50152).

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